Even in Los Angeles County, where hundreds of people are murdered each year, the three killings in a homeless encampment along the banks of Compton Creek stood out.

In death, the victims came to underscore the precarious, dangerous existence of homeless people in the county. Like many others scraping-out lives on the streets, they were in the grips of drug abuse or mental illness. And they belonged to a population that disproportionately falls victim to homicides and other violent crimes.

But little was known about their killer, other than the fact that he too was homeless. Now, through court records and interviews with his attorney, a detective who worked the case and others, a portrait comes into focus of a man submerged in a solitary, paranoid existence, who saw people either as “predators” or “prey.”

Tracy Walker does not dispute his crimes. He pleaded guilty to the three murders and recently was sentenced to 110 years in state prison. Ineligible for parole, Walker will die there.